alternative refrigerant – Explained
The environmental pressures of global warming have put increased emphasis on the need for alternative types of chemical refrigerants. The trend began in 1996, when the U.S. Environmental Protection Agency’s (EPA) Clean Air Act banned the manufacture of the most common refrigerants, because they contributed to the depletion of the ozone layer in our upper atmosphere that protects earth from the sun’s ultraviolet radiation. These refrigerants were known by the trademark name of their manufacturer, DuPont, as Freon 12 and Freon 22, although we will refer to them here by their generic names, CFC-12 and HCFC-22. CFC-12 is a chlorofluorocarbon (CFC), a chemical combination of carbon, chlorine, and fluorine. By clicking here we get info about alternative refrigerant
Chlorine is the culprit that zaps ozone. Under the EPA guidelines, CFC-12 was supposed to be phased completely out of use by the year 2000. In its place, related chemical compounds include hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs). However, HCFCs (HCFC-22) are also slated for extinction by the EPA somewhere between 2015 and 2030. HFCs, without chlorine, have skirted the ban so far; in fact, the most widely used alternative refrigerant is now HFC-134a. All refrigerants are hazardous when exposed to an open flame. Some of them contain butane or propane mixes blended into their formulas. If large quantities of refrigerant are released in a confined area, suffocation is a danger because refrigerant actually displaces oxygen.
Breathing refrigerant can cause nausea, dizziness, shortness of breath, and even death. Thus, any type of refrigerant gas should be handled by a professionally trained technician. Environmental risks and health warnings aside, the cooling power of the modern refrigerator comes from the repeated compression and expansion of a gas. As the gas expands, it cools and is cycled around an insulated compartment, chilling the contents inside. Ammonia, new chemical blends, and even space-age technology using sound waves to cool foods are other options that have been introduced recently with some success. In 2004 the ice cream maker Ben & Jerry’s installed the first thermoacoustic freezer in a retail location, developed by Penn State University researchers.
Thermoacoustics is the premise that, as sound travels through air, it alters the temperature of the air. A loudspeaker is used to create 170 to 195 decibels of sound (and yes, that’s very loud) in a tube that contains inert, compressed gases (helium or argon), which are environmentally safer than CFCs. The sound causes the gas molecules to vibrate, expand, and contract. When they contract, they heat up; when they expand, they cool down. In refrigeration, the goal is to exhaust the heat generated as the soundwave is compressed and capture the chill as the soundwave expands. The loud screech emitted within the unit is muffled so it is heard as a quiet hum from the outside. Thermoacoustics cools using a type of sealed motor developed in the 1800s by Robert Stirling of Scotland.
You may hear the term “Stirling cycle technology” associated with CFCfree coolant ideas. A Stirling motor can be solar-powered, which is one of its potential “green” advantages. Another promising cooling technology is electromagnetism. A “magnetic” refrigerator can cool by repeatedly switching a magnetic field on and off. The current prototype is made with gadolinium, a metal used in the recording heads of video recorders. Gadolinium and magnets are not cheap, but the technology shows great potential for two reasons: Electromagnetism is environmentally safe (no CFCs), and does not require a compressor (no mechanical humming noise as the refrigerator cycles on and off).